A nice set of wheels and tires help to set the tone for a vehicle’s appearance, but when it comes to drag racing, they’re also key ingredients in lowering your elapsed times. And if your car sees considerable street use, going to a race-oriented wheel and tire package will make your ride perform and look good doing it on the drag strip. For our Red Dragon Pontiac Trans Am project car, we determined that in order to reach our 9.99-second ET goal, we needed to ditch the stock wheels and go with some lightweight units from Race Star and wrap them in fresh Mickey Thompson rubber.
There’s more to making the switch to a drag racing-style wheel package for a street/strip car than just choosing wheels and tires that fit — they need to sync up with your intentions for the car and meet the criteria for the application. In this article, we hope to help you understand what to look for in wheels and tires for a dual-purpose car that’s driven to the grocery store as often as it makes quarter-mile passes.
The World Of Street/Strip Wheels
A good street/strip wheel will give you the heavier load ratings to drive on the street through the potholes and other obstacles, yet still give you a lightweight wheel you can win with on the strip – L.B. Davis
Part of what makes the wheels used on the street stronger is their weight. Because race-only wheels don’t have to go through the DOT J2530 testing required for street use, they are usually around 10-percent lighter than those used on the street. “When you drive the car through a pothole or up against a curb, the load rating on the wheel needs to be much greater with a wheel that’s used on the street. DOT test standards for driving wheels on the street are much tougher than the SFI standards for strip-only wheels, which have no cornering requirements in the testing for a wheel that is only used in a straight line,” says Race Star’s L.B. Davis.
The factory wheels that come on most performance cars are going to be 16-inches or larger in diameter, and with that size comes a lot of weight. The main focus of going to a wheel for street and strip use is to shed that weight, which will help reduce overall mass and rolling resistance. The biggest benefit of lowering the rolling resistance and weight is a quicker ET on your time slip.
“A good street/strip wheel will give you the heavier load ratings to drive on the street through the potholes and other obstacles, yet still give you a lightweight wheel you can win with on the strip,” Davis says.
Many racers might think that you have to purchase a full set of wheels for the track, but that’s far from the truth. If your car is doing well with stock size rear tires at launch, and you would like to lighten the car up, a safe bet is to only purchase the front-runners to improve on the ET. By playing with the wheel and tire size on the front of the car, in conjunction with sticky tires in the rear, a racer can use the wheels as a tuning tool for index or bracket racing.
For the Red Dragon, we’re using a full set of Race Star 92 Drag Star Dark Star wheels. Up front, a set of 15×3.75-inch wheels got the call, and they weigh just 12 pounds each. In the rear, a set of 15×10 wheels will be putting the power down to the track, which weigh in around 17 pounds. With the stock wheels weighing in around 20 pounds each, the weight savings overall with the wheels is 22 pounds of rotating weight. Where that weight savings is going to help the most is in the front end of the car, where we’re shaving off 16 pounds total. This reduced unsprung weight will be a huge help when the car is launching and will make weight transfer in the chassis more efficient, which is exactly what you want at the track.
What To Look For In Sizing And What To Avoid With Street/Strip Wheels
Getting the properly-sized wheels will really depend on what your car is able to handle. Most modern muscle cars come with large brake packages and will require a bigger wheel, in some cases, 17-inches or larger. Those bigger wheels might look great and fill some fender gap, but they won’t get you down the track any quicker. The best practice is to go with a smaller wheel for performance and as much tire as you can fit to get the most traction possible.
On average, you will see the best results with wheels for the front that are in the 15×3.75-inch range or larger, and in the rear a set of wheels in the 15×10-inch range is ideal. These wheel size ranges will allow you to drop some pounds and still be able to add a sticky tire to the back. If your car won’t allow you to go that small, a 17×4.5-inch to 18×5-inch on the front and 17×9.5-inch to 17×10.5-inch will work for the rear.
Davis does have some words of wisdom before you purchase or mount your new wheels.
“When purchasing your wheels, always be sure to test fit them before mounting the tires, as most return policies are voided once you have tires mounted on the rims. Also, be aware when you do suspension modifications because wheels that would normally fit on your car may no longer fit due to ride height and suspension variables.”
So, we’ve armed you with information on what to look for in street/strip wheels, but there are still some pitfalls you need to be aware of to avoid when making your wheel selection. First, be realistic with the application you’ll be using the wheels for and how much power you’re going to be putting down. Also, when driving with smaller wheels on the front, you have to adjust your driving style so you don’t roll the bead when taking a corner.
According to Davis, getting the rear wheel and tire size matched up is something that needs to be taken into careful consideration.
“In the rear of the car, it’s also important to match up the wheel and tire combination with the horsepower the car is producing. You always want to err on the side of too much tire, rather than not enough. It is important to be sure to have enough tire on the rear of the car to hook up the horsepower. You shouldn’t worry about how the size of the wheel looks when you are putting power to the ground because that won’t make your car any quicker or faster.”
Front And Rear Tire Talk For The Street/Strip
Wheels are just part of the equation that keeps your car rolling, and tires are what make the connection to the ground. For tires that see both street and strip duty, you want a tire with a compound that will be hard enough to deal with every-day driving, but also soft enough to grab the track surface when they’re heated up before you launch.
Jason Moulton from Mickey Thompson explains the biggest advantages a drag radial has over street tires at the track.
“A drag radial is just that — it’s designed with drag racing in mind, so it is compounded and constructed to provide superior traction over a standard street tire. For the drag racer who wants to drive on the street, a drag radial offers the flexibility to accomplish this with a tire that still has a DOT stamp.”
Track Time Air Pressure
It’s important to make sure you are running enough air in your tires on the drive to the track; but what about when you’re ready to make a pass? You will always need to analyze the current track conditions and weather before you make the final call, but running lower air pressure in the rear tires will allow for more flex in the carcass of the tire. That flex will let the tire take more power and provide better traction. When you run a higher air pressure in the rear tires, it will lower the rolling resistance and provide more stability at speed.
Some may ask, what about using a slick on the rear? It’s really not a great idea to drive on the street with a slick due to their construction and the lack of tread, because any amount of water could lead to disaster…not to mention it’s illegal.
According to Moulton, a slick can have some advantages at the track, but a DOT radial can do just as well and still be drivable. “Depending on the power level, track conditions, car set-up, and transmission, a slick may offer better traction, whether it’s a bias or radial slick. In many cases, though, the DOT tires can provide similar performance if the size is available.”
When you’ve made the choice to move to a skinnier front wheel, you will need a front-runner style tire to fit it. These tires will still need to have a DOT stamp to ensure they’re safe to use on both the street and strip. These tires will help your car perform better by helping to lower the ET due to lower weight and size.
“Front-runner or skinny tires in the front primarily provide benefits in reduced weight and rolling resistance. For street use, it’s important that the tire selected will maintain the load carrying capability of the tire originally equipped on the vehicle. You can also use different tire diameters to ‘tune’ your reaction times based on how your car is set up,” Moulton explains.
Clearing Up The Confusion With Street/Strip Tires
For the drag racer who wants to drive on the street, a drag radial offers the flexibility to accomplish this with a tire that still has a DOT stamp. – Josh Moulton
“There are many options available in DOT and non-DOT tires for drag racing. While they help meet specific needs, it can get confusing with all of the choices. Many think all ‘Drag Radials’ are DOT, however, Mickey Thompson offers two versions of the Drag Radial slick: the Pro Drag Radial for heads-up use and Pro Bracket Radial for bracket racing. In the end, if there is confusion, the best bet is to e-mail or call Mickey Thompson’s technical department.”
Another area where there is some confusion is what air pressure ranges should be used on both the street and strip. Running the correct air pressure is critical for the tire to perform well on the track, but also be safe for use on the street at highway speeds. Incorrect air pressures will also damage the tires and reduce their lifespan significantly, so adjusting them before you leave the track is important.
“For street use, a pressure must be used that will maintain the load carrying capability of the tire originally equipped on the vehicle. Mickey Thompson’s technical staff can assist on selecting the optimum pressure. It’s also important that the tire is equipped on a wheel width which is approved for the tire size selected. For selecting drive tire inflation pressure at the track, we have a Tech Bulletin on our website that can best provide guidelines for air pressure depending on the tire type, size, and weight of the vehicle that can be found right here,” Moulton says.
The right set of street/strip wheels and tires will not only make your car look good, they will help it perform better at the track on a regular basis. Selecting the right setup for your application is the best way to ensure you will minimize issues while driving on the street and get the performance you’re looking for on race day.